Presently, the three subtractive primaries are used to process silver halide color photographic light-sensitive materials, wherein color images are formed with a combination of the three dyes formed upon coupling reaction of a yellow coupler, a magenta coupler, a cyan coupler and a p-phenylenediamine-based color developing agent.
Magenta couplers used in conventional silver halide color photographic light-sensitive materials are pyrazolone couplers, pyrazolinobenzimidazole couplers, pyrazolonetriazole couplers and indanone couplers, of which various 5-pyrazolone derivatives are widely used.
Examples of groups used as the 3-position substituent for the 5-pyrazolone ring of the above 5-pyrazolone derivatives include alkyl groups, aryl groups, the alkoxy group described in U.S. Pat. No. 2,439,098, the acylamino groups described in U.S. Pat. Nos. 2,369,489 and 2,600,788 and the ureide group described in U.S. Pat. No. 3,558,319. However, these couplers have some drawbacks; for example, the coupling activity with the oxidation product of developing agent is low, high densities of magenta dye images cannot be obtained, the magenta dye image obtained by color developing has great secondary absorption in the blue light band, and the sharpness of the primary absorption on the long wavelength side is poor.
Also, the 3-anilino-5-pyrazolone couplers described in U.S. Pat. Nos. 2,311,081 and 3,677,764, British Patent Nos. 956,261 and 1,173,513 and other publications offer advantages such as high coupling activity for good coloring performance and little undesirable absorption in the red light band. However, these conventional 3-anilino-5-pyrazolone couplers pose a problem of deterioration of color reproducibility etc. when they are used in color negative silver halide photographic light-sensitive materials because their primary absorption is in relatively short wavelengths.
It has recently been found that in using a color negative film for printing on color printing paper, there is variation in the hue of the finished color print among the printing machines used (hereinafter referred to as printers), which variance is hereinafter referred to as variation among printers, and that this is partially attributable to the tone of the dye resulting from the magenta coupler used in the color negative film.
It has also been found that this variation among printers widens significantly when the above-mentioned 3-anilino-5-pyrazolone couplers are used.
Although significant improvement in variation among printers is achieved by the use of the magenta coupler described in Japanese Patent Examined Publication No. 30615/1980, the level reached remains unsatisfactory.
Also, with the recent trend toward format size reduction in photographic light-sensitive materials and the popularization of panorama prints (panoramic exposure is given to the central portion of a 35 mm film, the exposed portion printed wide latitudinally), there has been demand for a photographic light-sensitive material offering high sharpness and high image quality. The image quality offered by a silver halide photographic light-sensitive material depends on various factors, including silver halide grain size. It is known that size reduction in the silver halide grains used is very effective in improving image quality; there is demand for a technology offering high sensitivity with small-sized silver halide grains.
It is obvious to those skilled in the art that certain polymethine dyes are very effective in spectrally sensitizing silver halide emulsions, including the various types of compounds described by T. H. James on pages 194-234 of "The Theory of the Photographic Process", 4th edition (1977, MacMillan, New York). These sensitizing dyes are required not only to broaden the sensitivity wavelength range of the silver halide emulsion but also to meet the following requirements.
1) To offer appropriate spectral sensitization by the sensitizing dye.
2) To have high sensitizing efficiency and offer sufficient sensitivity.
3) To be free of fogging.
4) To exhibit no adverse interaction with other additives such as stabilizers, antifogging agents, couplers, oxidized developer scavengers and coating aids.
5) To undergo neither dye desorption nor sensitivity reduction when the silver halide coating emulsion containing the sensitizing dye is kept standing for a long time.
6) To cause neither increase in fog density nor sensitivity reduction when the silver halide light-sensitive material containing the sensitizing dye is left under high-temperature high-moisture conditions for a long time.
7) To cause no color cross-over (color mixing) after development as a result of diffusion of the added sensitizing dye into another light-sensitive layer.
To meet these requirements, which are significant in preparing a silver halide emulsion, various compounds have been proposed and synthesized. Particularly azole ring trimethinecyanine dyes having a chalcogen atom in the ring thereof, such as thiacarbocyanine, oxathiacarbocyanine, selenacarbocyanine and oxaselenacarbocyanine, are known as principal red sensitizers having a preferable spectrum sensitivity in the red light band and offering excellent spectral sensitizing efficiency. Examples of such dyes include the cyanine dye described in U.S. Pat. No. 3,615,644, wherein an alkoxy group is present as a substituent on the condensed ring, the thiocarbocyanine dye described in U.S. Pat. No. 2,429,574, which has a methylenedioxy substituent, the thiacarbocyanine dye described in U.S. Pat. No. 2,515,913, wherein a phenyl group is present as a substituent at the 5 position, the thiacarbocyanine dye described in U.S. Pat. No. 2,647,050, wherein a carboxyl group is present as a substituent at the 5 position, the thiocarbocyanine dyes described in U.S. Pat. Nos. 2,647,051 and 2,647,052, wherein an alkoxycarbonyl group is present as a substituent at the 5 position, the carbocyanine dye described in U.S. Pat. No. 2,485,679, wherein a phenyl group is present as a substituent at the 6 position, the saturated carbon ring condensed thiazolocarbocyanine dye described in U.S. Pat. No. 2,336,843, the various other carbocyanine dyes described in U.S. Pat. Nos. 1,846,302, 2,112,140 and 2,481,464 and other publications, the trimethine dyes described in U.S. Pat. Nos. 2,369,646, 2,385,815, 2,484,536, 2,415,927, 2,478,366, 2,739,964, 3,282,932 and 3,384,489 and other publications, wherein a substituent is present on a carbon atom in the methine, the trimethinecyanine dyes described in U.S. Pat. Nos. 2,647,053, 2,521,705 and 2,072,908, British Patent No. 654,690, Japanese Patent Examined Publication No. 21711/1961 and other publications, wherein an anion group is present as a substituent, and the oxathiacarbocyanine dye described in British Patent No. 1,012,825. Some of these carbocyanine dyes, when used singly or in combination, meet the requirements described above. However, staining resulting from the residence of the spectral sensitizing dye in the light-sensitive material after developing (hereinafter referred to as residual staining) was found a cause of the above-described variation among printers. In this regard, conventional carbocyanine dyes proved unsatisfactory.